<template>
  <div>
    <p>请选择你要购买的书籍</p>
    <ul>
     <li v-for="(item,index) in arr" :key="index">
      {{ item.name }}
      <button @click="addBook(index)">买书</button>
     </li>
    </ul>
    <table border="1" width="500" cellspacing="0">
      <tr>
        <th>序号</th>
        <th>书名</th>
        <th>单价</th>
        <th>数量</th>
        <th>合计</th>
      </tr>
      <tr v-for="(item,index) in arr" :key="index">
       <td>{{ index + 1  }}</td>
       <td>{{ item.name }}</td>
       <td>{{ item.price }}</td>
       <td>{{ item.count }}</td>
       <td>{{ item.price * item.count }}</td>
      </tr>
    </table>
    <p>总价格为: {{addPrice}} </p>
  </div>
</template>

<script>
export default {
  data() {
    return {
      arr: [
        {
          name: "水浒传",
          price: 107,
          count: 0,
        },
        {
          name: "西游记",
          price: 192,
          count: 0,
        },
        {
          name: "三国演义",
          price: 219,
          count: 0,
        },
        {
          name: "红楼梦",
          price: 178,
          count: 0,
        },
      ],
    };
  },
  methods: {
   addBook(ind) {
    this.arr[ind].count++
   }
  },
  computed:{
   addPrice() {
    return this.arr.reduce((item,obj) => {
     item += obj.price * obj.count
     return item
    },0)
   }
  }
};
</script>